All vulnerabilities
CVE-2026-90771GHSA-wr44-6hxh-3jwq

joi messages compilation allows prototype replacement through __proto__ error codes

hapijs joinpmLibraries & packages
Open in ThreatlineRecord JSON
CVSS
6.3Medium
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 16 Sep 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.39%Chance of exploitation activity in the next 30 days, higher than 31% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in17.13.8Also 18.2.9GitHub
Published13 Sep 2026Updated 5 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

joi before versions 17.13.8 and 18.2.9 contains a prototype pollution vulnerability in the messages compilation function that accepts __proto__ as an error code. Attackers can supply __proto__ keys in custom messages to replace the returned object's prototype, breaking downstream code relying on Object.prototype methods.

Text from CVE List

Affected versions 6

  • joi, npm< 17.13.8GitHub
  • joi, npm>= 18.0.0, < 18.2.9GitHub
  • joiaffected: 16.0.0 before 17.13.8CVE List
  • joiaffected: 18.0.0 before 18.2.9CVE List
  • joi, npmfrom first release, fixed in 17.13.8OSV
  • joi, npmfrom 18.0.0, fixed in 18.2.9OSV

References 12